Peocess of peodttcibtg algin compototds and pbodttcts deeived thebefeom



Patented Apr. 19, 1927.

UNITED STATES TENT OFFICE.

BERNARD, TE. ERDAHL OF DULUTH, .MINNIESOTA.

PROCESS OF PRODUCING ALGIN COMPOUNDS AND PRODUCTS DERIVED "THEREFROM.

No'Drawing'.

' rial, algin'is abstracted from sea Weeds in such a form as to dissolve'in cold water and form a collodial solution. ,For example, the comparatively pure alkali or alkaline base of alginic sea weeds is dissolved in cold water varying in temperature from 32 to is the preferred raw material.

chloric, nitric, or sulfuric acid may be used. as the precipitating medium. The most sat- 70 F. producing a collodial solution. The concentration and viscosity of the colloidal solution may vary according to circumstances. However, most satisfactory. results for subsequent processing are obtained when;

using a ten per cent colloidal solution of an algin base. Sodium alglnat'e serves admi- 'rabl-y as a basic raw material. The sodium alginate should be relatively pure, as free from cellulose as possible. Such inorganic impurities as remain are generally removed in the subsequent acid treatment;

In carrying out my invention, a colloidal solution of an algin base prepared as above described, for example, a ten per cent collo dal solution is treated with an acid which hydrolyses or dissociates to agreat degree. The'colloidal solution of the algin base may be prepared by dissolving 300 pounds of dry sodium alginate; in 3000 pounds of water. The colloidal solution is preferably an alkali metal solution of an alginate. Other soluble algin bases are suitable but sodium alginate Hydrois'factory'results are obtained with a dilute solution of sulfuric acid, and it is of considerable importance that the concentration of the acid beof the proper degree. For

practical purposes, the concentration of the acid may vary between a 17% to a 9% .solution by volume depending on the time of the Application filed July 20, 1926. Serial 'iNo. 123,808.

digestion of the precipitate produced by adding a collodial sodium alginate solution to an acid bath. I have :found that satisfactory results maybe obtained by-adding to the 10% alginate solution, which, as stated, is prepared by treating 300 pounds of dry sodium .alginate with 3000 ounds of '1water, 425 gallons of dilute su phuric acic. with the alginatc. About halfof'the'sulphuric acid is spent in one precipitation, the other half being recovered and used over again for the next concentration, fresh sulphuric acid being added'thereto, if necessary.

This is more than sufiicient tore'act;

In effecting the solution of the colloidal sodium alginate in the acid bath, it is a necessary precautlonto keep both the colloidal solution of the alginate and the aid bath I cool. A temperature ranging between 32 and 70 F. is satisfactory. The colloidal alginate solution is fed into anozzle constructed so as to provide a thin wide ribbon of cOlloidalrodium alginate as it leavesthe nozzle. The ribbon of the cold sodium alginate. as it comes from the nozzle, is gaged with the acid on leaving the nozzle and then dropped into a bath of dilute sulfuric acid and the resulting precipitate retains the ribbon form. The acid bath is slowly stirred as the precipitation is eifected. This ribbon precipitate is aged by digestion in the acid bath for a varying period of time, depending upon the strength of'the acid used. When the concentration of the sulfuric acid is about 9% by volume, the digestion and aging period is about24'hours. When a higher acid concentration is used. the digestion and aging period is shorter. In all cases a suiticient quantity of acid should be present "to effect a complete reaction. The step of dinesting and a ring the algin precipitate is an important'one as it allows the chemical reaction occurring when the colloidal sodium algrinate solution is introduced into the acid bath to be substantially completed. This is essential as I have discovered that incomplete precipitation in the absence of the aging step results in a product which is inble therein. On the other hand, the digested algin resulting from aging in an acid bath gives a product which goes into colloidal solution almost instantly on contact with ammonia.

'When the colloidal solution of sodium alginate is introduced into the bath, chemical action occurs and the sodium alginate reacts with the acid. The alginic base adsorbs the metallic hydrogen ion and the sodium is liberated as the sulfate, chlorid. or other salt depending on the nature of the acid used. If hydrogen is considered as a metal, the resulting alginate may be called a metal alginate. After the aging step, the resulting precipitate is washed with cold water to remove the salts and excess precipitating liquor. It is quite important that the precipitate be thoroughly washed and the last traces of impurities removed. The purified precipitate according to ,an ultimate analysis corresponds to the formula C H O This precipitate is dried by any appropriate means, for example, by centrifugal force until it has a consistency corresponding to 20 to 25% solids.

The alginic acid prepared as set forth may be dissolved directly in ammonium hydroxid or any other solvent in which it will go into colloidal solution. However, in the preferred form of my invention, the use of a fortifying agent is contemplated. The fortifying agent may comprise a vegetable or animal wax or an oil capable of being saponified and emulsified by a medium capable of removal by evaporation.

Specifically, the fortifying agent is prepared as follows: Beeswax is heated witha measured excess of ammonia, until that part of the wax consisting of the fatty acids or other corresponding oils or esters is almost completely saponified. The heating may be carried out in an autoclave or other closed vessel at a temperature. varying between and 100 C. The autoclave treatment will effect the saponification of the fatty acids or their corresponding oils or esters and produce an emulsion of the saponifiable and unsaponifiable compounds present. When the mixture is thoroughly saponified and emulsified the semi-liquid is cooled down to about 70 C. and the liquid is gaged on the precipitate of alginic acid in a closed mixer. [n the mixer the excess ammonia present in the fortifying mixture dissolves the precipitate of alginic acid forming ammonium alginate. The pro portion of the fortifying agent to be added to the alginic acid precipitate may vary in accordance to the uses to which the final product may be applied. Satisfactory results are obtained when five pounds of the alginic acid precipitate is mixed with the emulsion obtained from one pound of wax or oil.

The mixed end product which is ammonium alginate containing the products of decomposition, that is saponification and cmulsifieation products resulting from a'dding the fortifying agent is soluble in water. On drying, by heating, vacuum treatment, aeration, or the like, this product becomes insoluble as the ammonium alginate decomposes, as do the saponified and other emulsified compounds, the product thereby becoming free of the dispersing agent. Due to the removal of the volatile dispersing agent and the decomposition of the alginate, and the saponified compounds, the end product on application to a pervious material will-leave a film that is substantially colorless, nonpoisonous, cohesive, adhesive, continuous or non-porous, water repellant and acid resistmg.

From the above it will be seen that my invention consists broadly in preparing an algin material by introducing the colloidal solution of an algin base into an acid bath, aging the resulting precipitate in said bath, and recovering the algin reaction product therefrom. This produces an intermediate material from which alginates containing a volatile radical may be prepared. Various algin bases may be used but in the preferred form of my invention, I contemplate using purified sodium alginate. Various acid baths of different concentractions may be used and depending upon the concentration of the acid bath, the period of digestion and aging varies. Miy invention also consists in mixing the aged algin precipitate with a volatile dispersing agent such as ammonia containing a fortifying agent, but it is to be clearly understood that my invention is not restricted to the use of the particular volatile dispersing agent referred to. It has been set forth as an example because it is the most suitable one to work with. As indicated, the fortifying agent may consist of a saponifiable material dissolved in ammonia, the

vegetable and animal waxes or oils serving admirably for this purpose. It is preferred to use beeswax as most satisfactory results have been obtained when using this material. However, other waxes, such as Japan Wax and myrtle wax may be used.

The yuecipitate formed by adding a sodium 'alginate solution to the acid is a solid, which, after being centrifuged, resembles coarse saw dust. It is not as hard 'to the touch as saw dust. This n1aterial, although it contains T5 to 80% of water, 25'to 20% of solids, only feels slightly moist to the touch. As the material comes out of the bath and before being centrifuged the precipitate con tains from 96 to 98% water. This precipitate is a solid colloid.

The material produced by adding the fortifying agent, which, as stated, is an emulsion, to the solid aged alginic acid assumes the form of a thick colloidal solution or of'the cellular or pervious materials.

paste, somewhat similar to thick molasses. It is so thick that it barely runs. The ammonium alginate produced when using a measured excess of ammonia in the fortifying emulsion gives a glue-like or syrupy compound,

Such a film is adapted to the waterproofing and acid proofing of various materials, when used integrally and as a sizing. The

film will withstand the action of the diluted acids and of concentrated acids excepting concentrated sulfuric acid. It may be used between 120. and 140 F. to eflect the removal of the'water and the volatile ammonium dispersing agent.

Cellular or pervious materials or articles may be treated with the fortified ammonium alginate prepared as described to form a filling, coating, envelope or impregnatlipln e extent to which the filling permeates the cells or interstices of the material and becomes interlocked with the same depends upon the methods used to produce the material and fabricate the article. Both inorganic and organic cellular or semi-cellular and pervious materials may be treated with the fortified ammonium alginate as prepared with conferment thereto of many desirable properties.

The fortified ammonium alginate, as described, may be mixed with or caused to impregnate wood pulp, paper or other cellular or pervious materials either in the raw or finished state. When wood pulp and paper pulp are used to form weather boards, roofing slabs, roofing paper, flooring and similar fabricated articles, it is preferred to add the colloidal fortified ammonium algfiiate to the material in bulk, before it is manufactured into the desired article, but the finished articles may be treated with the fortified ammonium alginate by simple im mersion. In either case, care must be taken to subject the finished composition of matter or article to a thorough drying and gradual heating, in order to decompose the ammonia soaps and liberate ammonia from the ammonium alginate, leaving an insoluble, impermeable, cohesive, adhesive,continuous or non-porous, water repellant and acid resisting film. It is preferred to heat gradually and a maximum temperature of 140 F. has

been found satisfactory. Obviously,the de gree to which the articles are heated wil vary according circumstances.

The impregnation of the material may be effected or facilitated by any other well known methods, as for instance, slight heating, vacuum impregnation, injection by force under pressure, or the fortified ammonium alginate may be applied by simple soaking or the immersion of the material therein.

The fortified colloidal solution of ammonium alginate prepared as described is suitable for the treatment of materials such as vegetable fibers, fabrics or cotton, jute, flax, silk, wool, inorganic substances such as artificial stone, asbestos, and cementitious mixtures containing asbestos and a filler.

lVhen the colloidal fortified ammonium alginate is added to the material in bulk, the resulting product may be pressed or shaped as desired, by mold-treatment or may be prepared in the form of a slab or in a regular or irregular mass which may be cut, sawed, turned or otherwise manipulated to any desired form or size.

' Materials or articles coated with the fortified ammonium alginate possess excellent and impregnating of all types of paper materials and containers made from the same.

The terms fortifying and fortifying agent, as used in the specification and claims, apply to any material which will olfset any defect in the preparation of the final algin product and, in addition, will serve to increase the desirable properties of the film such as impermeability, cohesiveness and, in-

general, its r'esistent properties. In general. it may be stated that the term fortifying agent is well known in the art, as specifically indicated in my U. S. Patent No. 1,415,324., May 9, 1922.

The expression alginic acid, which has been aged in an acid bath is intended to define a material which has been digested in the acid bath for such a period of time as to have the property of going into colloidal solution substantially instantly on contact with-the volatile dispersion agent, such as ammonia. By this term I wish to distinguish between my new product and that resulting from simply adding the acid to the algin solution without allowing suflicient As the fortified ammonium al-- time for the reaction to be completed, which is the prior art method of carrying out the reaction.

I claim:

1. The process of preparing an algin material comprising introducing a colloidal solution of an algin base into an acid bath, aging the resultng precipitate in said bath, and recovering the algin reaction product therefrom.

.2. The process of preparing an algin material comprising introducing a colloidal solution of an algin base into an acid bath, aging the resulting precipitate in said bath,

washing the precipitate with a cold fluid and recovering the algin reaction product.

3. The process of preparing an algin material comprising introducing a colloidal solution of an algin base into a dilute sulfuric bath, aging the resulting'product in said bath and recovering the algin reaction product.

4. Alginic acid which has been aged in an acid bath.

5. The process of preparing ammonium alginate comprising treating an algin base with a dilute acid bath which highly hydrolyzes, aging the resulting precipitate in said bath, washing the precipitate to remove the impurities therefrom, and dissolving the precipitate in a volatile dispersing agent.

6. The process of preparing ammonium alginate comprising treating an algin base I 1 with a dilute acid bath which highly hydrolyzes, aging the resulting precipitate in said bath, washing the precipitate to remove the impurities therefrom. and dissolving the precipitate in ammonia.

. 7. The process of preparing ammoniumalginate comprising treating an algin base with a dilute sulfuric acid bath, aging the resulting precipitate in saidbath, washing the precipitate to remove the im urities therefrom, and dissolving the precipitate in a volatile dispersing agent.

8. The process-of preparing ammonium alginate comprising treating an algin base with a dilute sulfuric acid bath, aging the resulting precipitate in said bath, washing the precipitate to remove the impurities therefrom, and dissolving the precipitate in ammonia.

9. The process of preparing a fortified alginate comprising treating an algin base with a dilute acid bath which highly hydrolyzes, aging the resulting precipitate in said bath, washing the precipitate to remove the impurities therefrom, and mixing the precipitate with fortifying compounds emulsified in a volatile dispersing agent carrying an excess of the dispersing agent adapted to be removed on drying of the fortified alginate.

10. The process of preparing a fortified alginate comprising treating an algin base with a dilute sulfuric acid bath, aging the resulting precipitate in said bath, washmg the precipitate to remove the lmpurities therefrom, and mixing-the precipitate with fortifying compounds emulsified in a volatile dispersing agent carrying an excess of the dispersing agent ada ted to be removed on drying of the fortifie alginate.

11. The process of preparing fortified ammonium alginate comprising treating an algin base with a dilute acid which highly hydrolyzes, aging the resulting precipitate in said bath, washing the precipitate to remove the impurities therefrom, and mixing the precipitate with fortifyingcompounds emulsified in an ammonium dispersing agent carrying excess ammonia adapted to be re moved on drying of the fortified alginate.

12. The process of preparing fortified am-' excess ammonia adapted to be removed on drying of the fortified alginate.

13. The process of preparing fortified ammonium alginate comprising treating an algin base with a dilute sulfuric acid bath, aging the resulting precipitate in said bath, Washing the precipitate to remove impurities therefrom, and mixing said precipitate with a fortifying agent comprising a saponifiable material emulsified in a volatile dispersing agent.

14. The process of preparing fortified ammonium alginate comprising treating an algin base with a dilute sulphuric bath. aging the resulting precipitate in said bath, washing the precipitate to remove impurities therefrom, and mixing said precipitate with a fortifying agent comprising a saponifi able material emulsified in ammonia.

15 Aged alginic acid dissolved in ammonia. I

- 16. Aged alginic acid dissolved in ammonia and carrying a fortifying agent.

17 Purified aged alginic acid mixed with a fortifying emulsion carrying ammonia.

18. Aged alginic acid mixed with a wax emulsion.

19. Aged alginic acid mixed with an emulsion of bees wax.

20. Aged alginic acid mixed with an ammonia emulsion of wax.

v 21. Aged alginic acid mixed with an ammonia emulsion of bees wax.

22. Purified aged alginic acid mixed with an ammonia emulsion of bees wax.

23. As a new article of manufacture, a pervious or cellular material carrying the decomposition products produced by impregnating the material with a purified aged,

l-ular 0r pervious material carrying a cohesive, adhesive, continuous impermeable filling or film resulting from the treatment with aged alginic acid mixed with a fortifying agent containing an ammonia emulsion of beeswax, and removing the ammonia.

In testimony whereof he hereunto affixes his signature.

BERNARD F. ERDAHL. 

